Apparatus for drying paper



Aug. 25, 1925.

H. H. HANSON ET AL APPARATUS PQR DRYING PAPER 1 l l l I I I l l l l I 1l ll 7 t A ,M w/ 7 v w Ll M @Nw A A 4 w n v .JW m m5, 6. 9W w3 KS NQ R mJ m S Am AQ @f h fil r E -,:utwa .9,--- @5-0i A@ 1.9. 11.0.-- VNU@ MQ aQS A O C f. 0 C\f.\ O o O C o e @IOIQNAH -zmwmw WQJX \x,\\ \|w\ IPL .Il1 :gw Q Nl .RS bm) l ,in m w .lm \w\ m w n H. H. HANSON ET AL APPARATUSFOR DRYING PAPER Filed Jan. 26. 1.921. 4 Sheets-Sheet 2 Aug. 25, T925.

1,550,695 H H HANsoN ET Al.

APPARATUS FOR DRYING PAPER Filed Jan, ze, 1921 4 sheets-sheet s w m @NQS kw Aug. 25, 1925.

H. H. HANSON ET AL APPARATU-S FOR DRYING PAPER Flled Jan. 26. 1921 4Sheets-Sheet 4 Patented Aug. 25, 1925.

UNITED STATES HUGO H. HANSON, CF BOSTON, MASSACHUSETTS, AND WILFRED A.WYLDE, OF BAN'-y s 1,550,695 PATENT oFFlcE. f

GOB, MAINE, ASSIGNORS TO EASTERN MANUFACTURING COMPANY, OF BOSTON,MASSACHUSETTS, A CORPORATION F MASSACHUSETTS. i

nAPPARATUS FOR DRYI-NG PAPER.

Application iled January t26, 1921. Serial No. 440,173.

To all 'whom t may concern:

Be it known that We, HUGO H. HANsoN and 'WILFRED A. WYLDE, both citizensof the United States, and residents of Boston, in

the count of Suffolk, State of Massachusetts, andY of Bangor, in thecounty of Penobscot and State of Maine, have invented new and usefulImprovements in Apparatus for Drying Paper, of which the fol-x 10 lowingis a specification.

This invention has for its object to produce a high grade Writing aperhaving the characteristics of "loft-dried) paper but with greaterstrength, by a continuous process.y

l5 Loft-dried paper is characterized by a eertain fcockle, due to themanner in Which the paper is dried.- It comprises the three papers knownusually as bond, ledger and linen finished papers. Ledger paper andlinen finished paper, the first because of the character of thecalendering which is ernployed in its manufaeture,.and the second ecauseof the plating operation to which it is submitted, do not possess thecockle to the same extent as bond paper, but all three have to a certainextent that cockle which is characteristic of loft-dried paper.

In the loft-drying of paper, as usually carried out, the dry web fromthe dry end 0f the paper machine is carried through a` tubsiZingbatli,then slit and cut into sheets and arranged in Vpiles or packets. yEachpacket is then hung over a pole in a loft or -drying chamber, andsubjected to a tem- 5 perature of approximately -120o F. until dried.The period required ,for the drying operation varies froih fifteen toeighteen hours, andthe total `time for hanging, 'drying and pulling a.paper so loft-dried 4 vtakes from thirty to thirty-four hours. The

process is, therefore, not continuous, andy apart as they would be ifthe drying took' place under restraint, and consequently the paper,possesses greater strength than one Which is dried under constraint asin the usual drying machine having the characteristic drying rolls andfelts. Second, because the paper feels firmer 'to the touch and has whatis called a better tone As stated, such papers, and artieularly bondpapers which are not hig ly calendered in finishing, retain a cockledsurface, due to the shrinkage of the fibers, which is highly desiredbythe trade and is regarded as the characteristic of a high gradeWriting paper.

Due to the fact that the drying of paper by the loft process isexpensive, various attempts have been made tovduplicate loftdried paper,especially bond paper, hy coutinuous processes, but, so far as we know,t-hese attempts have been unsuccessful` producing only air-dried paperwhich lacked the appearance of loft-dried paper and has less commercialvalue,-this being particularly true in heavier paper on which a cockledsurface is difficult to obtain.

In accordance With our process the paper is dried continuously in theweb, after having been subjected to the tub-sizing operation, and afterbeing dried may be cut into sheets of the desired length. Bearingin mindthat the paper must be free from constraint during the drying operationso as to permit the fibers to shrink to the desired extent and give thepaper the highl \v desirable cockled appearance, We carry ,on theprocess in such manner that the paper is at no time required to sustainits own weight. except for short lengths in which its weight isinsufficient to have any tendency to pull the fibers apart. That istoisay, instead of festooning the paper or in causing it to pass up anddown alternately over and under rolls which are arranged in different.horizontal planes, we make provision for the paper to travel forconsiderable distances in a horizontal plane, during which time it issupported looselyon rolls upon which it may rest, and which, if desired,may he rotated so as to prevent the surface of the paper from beingdragged thereover and to assist in causing the longitudinal travel ofthe paper. It is possible, of course. to have the drying operationcarried on while the paper is traveling continuously in a horizontaldirection so that entering the drying and is then dried as hereindescribed to a' point where it contains not over 5 to 6% of moisture,the resulting paper will not only possess the highly desired cockledappearance and tone, but will possessa marked increase in strength overpaper which has been dried to a bone-dry condition before it issubjected to the sizing operation.

We have further found that itis possible to expedite the dryingoperation by -heating the drying atmosphere to a temperature ofapproximately 240 F. It has heretofore been regarded as dangerous forthe paper, to employ a drying atmosphere heated to the temperaturementioned and, of course, it will be readily understood that if paperwere in fact held at to suth a temperature for any considerable lengthof time, its fibers would be injured and the paper would be brittle andundesirable. Such a condition does not exist for the reason that therapid evaporization of moisture from the paper keeps the temperature ofthe paper itself very much below that of the surrounding air: forexample, paper containing 12% moisture showed a temperature under 120 F.in an atmosphere well 'above 200 F. Thus the time during which the paperis at a high temperature is exceedinglyshort.

In an yapparatus for carrying out the proccss as hereiiroutlined, duringwhich the paper is dried as it is traveling without constraint in ahorizontal direction, provision must be made for effecting adifferential rotation of the rolls by which it is supported in order tocompensate for the shrinkage of the web during the drying operation, andtherefore we provide means b which the various supporting rolls may e sodriven that their peripheral speed is e ual to or greater than thedesired speed o travel of the web, and yetby which they are driven atdifferential, speeds at different .points in the travel of the web.Thus, as the drying of the paper progresses and the web shrinks, thesuccessive rolls are driven at a decreased surfacespeed, as a result ofwhich tension on the' web is eliminated.

In the accompanying drawings we have illustrated more or lessdiagrammatically and conventionally an apparatus embodying our inventionby which our process may be practiced in connection with sized paper,but lit will be understood, of course, that many changes may be made inthe yapparatus as illustrated without departing from the spirit andscope of our invention.

Referring to said drawings:

Figures 1 and 1A represent the dryin apparatus in side elevation, therebeing illustrated at the left of Figure l a portion of the dry end of apaper machine, certain winding reels and a tub sizing apparatus, allillustrated conventionally.

Figure 2 represents a plan view of the air supply chamber of the loft ona smaller scale, being more or less diagrammatic for the purpose ofillustrating the circulation of the drying atmosphere.

y'Figure 3 represents an end elevation of the apparatus.

Figure 4 represents diagrammaticall the first tier ofhorizontal rollsover Whic the web passes after entering the loft and illustrates more orless conventionally the mechanism for drying the web on said rolls.

yFigure 5 is a similar view illustrating the second or intermediate tierof rolls.

Figure 6 is a similar view'7 illustrating the lowest or bottom tier ofrolls.

Figure 7 illustrates the transmitting mechanism for transmitting powerfrom the main drive shaft to a series of rolls in each of the threeltiers.

Figure 8 represents the end of .the web which is formed with a tailreparatory to its being carried through the oft by an initial paperfeeding apparatus with which theloft is equipped.

On the drawings, reference being hadiat yuntil it has a very lowmoisture content, it

is so weakened that when subjected to the further sizing and dryingoperation it does not possess what we regard as a desirable strength. Weshould not regard it as a departure from our invention, however, if thepaper were dried to a greater extent, so far as other features of ourprocess are concerned.

At B we have indicated conventionally a reeling apparatus by which theweb delivered from the paper machine may be coiled or wound into rolls,and removed for storage or otherwise. At C is indicated a supplementalreel stand, on which the rolls may be' located if it be desired to passthe Lament 8 web therefrom through the drying apparatus or continuouslloft described. If desired, neither of these reel stands is employed,but the paperA is transferred directly from the dry end of the papermachine to the sizing tub which is indicated at D. This sizing tub isillustrated conventionally, beng provided With a vat d in which the bathof sizing'compound isl contained, and in which it is maintained at thedesired temperature by the usual means. 1t is also provided with theusual squeeze rolls e and b for removing the excess sizing compound fromthe paper. g indicates a guide roll over which the web passes on its Wayto the loft.

The loft which may be utilized in carrying out our process, consists, asstated, of a plurality of rolls arranged with their axes approximatelyin a horizontal plane, though, of course, it is not essential that theplane of the axes should be strictly horizontal, as the plane might beinclined, if desired. The point is that the paper is not caused totravel up and down, over and under alternate rolls disposed in differenthorizontal planes, but is caused to travel over a series of rollsarranged in approximately the same plane, during which time it iswithout constraint so that the paper is permitted to shrink and dry. Thedrier is, therefore, comparable With a loft, but without thedisadvantages due to hanging packets of paper over rods or poles bywhich a curvature is set in each sheet.

le could, as previously indicated, employ a single long tier of yrollsso that the paper would travel practically without deviation during theentire period of drying, but for mechanical purposes we prefer toarrange the rolls in horizontal tiers, one over the other, therebydecreasing the length of the drying chamber. In its sim lest aspect `theloft comprises an oblong cas ng formed of any suitable material which isapproximately air-tight, and in which the rolls of the several tiersmaybe journaled, andwith y means for circulating a highly heatedatmosphere through the casing.

In Figure 1, in which the loft or drier vis more or less conventionallyillustrated, a

' thesizing tub through a narrow slot` or opening in one end wallof thechamber, and, passing over the top tier of rolls, descende, travels inthe opposite direction over the intermediate tier ofrolls, descendsagain and travels forwardly on the lower tier of rolls and is finallyldelivered through a narrow slot or throat in the other end wall of thechamber and i's'then Wound into rolls, as Will 'be described. During thetime' that it travels over the rolls of the sevferal tiers, it issubjected to a highly heated atmosphere which is kept continuousl incirculation so that the web of paper is ried to the `desired extent. Themechanism by which the` heated atmosphere is supplied and maintained incirculation will subsequently be described. y 'p As we have previouslystated, it is desir'- able and, in fact, necessaryv that the rolls inthe several tiers should` be driven at different speeds in order tocompensate for the shrinkage of the paper web, this being particularlytrue of the end roll in. each tier over which the web passes previous toits being delivered to the next, succeeding tier of rolls. These endrolls should, of course, be rotated so thatl their peripheral speed is`equal to thespeed of travel of the web, but the other rolls of the tiermay be driven at a peripheral speed somewhat higher than the speed oftravel of the web so as toassist in feeding it throu h the drier.

Any suitable di erential driving mechanism may be utilized for impartingpower to the several rolls in the different tiers. We have illustratedconventionally a main driving shaft' 14 (see Figures 4, 5 and 6) Awhichis located outside of the main drying chamber or loft and which extendslongitudinally' thereof. This shaft is,'of course, mounted in suitablebearings and it is drivenfrom any suitable source of power byvariablespeed power-transmitting mechanism. For this purpose, we mayemploy, if desired, an initial driving shaft 15 receiving its power froma motor or a counter-shaft, and for. this purpose being equipped with a'driving pulley 16. The shaft 15 is illustrated as being provided with acone pulley 17, which, by the medium of a belt 18, drives a parallelcone pulley 19 on a shaft\20, which, by al belt'21 and pulleys 22, .23,drives the shaft 14. Bymoving the belt 18 lengthwise ofthe pulleys 17and 19, the shaft 14 may be driven at any desired speed, notwithstandingthe initial power shaft may be driven at constant speed.

1n Figure 4, we have illustrated the rolls of the first tier. Y These`rolls comprise the two end rolls l24, 25, and intervening groups ofrolls which are indicated at 26, 27 and 28.

The'end roll 24 is theone over which the",y

web initially passes as it, enters the drier, and the roll 25 is the oneover which the web passes on its-way to the second tier of rolls. Thislast-mentioned roll 25 is of large diameter, say, preferably, 24 to 30inches, so that by its use we are able toavoid the 'fortively small'diameter.

mation oflongitudinal wrinkles in the web, for we have found that, wherea roll of smaller diameter is employed, there is a constant tendency forthe damp web to form longitudinal wrinkles Orpleats.

The rolls 26, 27 and 28 may all be of rela- The rolls 26 of the firstseries are illustrated asydriven from a shaft 29 which, in turn, isdriven by a belt 30 and pulleys '31, 32, from the main variablespeed-driving shaft 14. We have illustrated the shaftsof the rolls 26 asbeing provided with bevel gears 33 intermeshing with and driven 'bycomplemental gears 34 von the shaft 29. For driving the firstl roll 24,aV

short supple-mental shaft 35, driven by bevel gears 36, 37 (tl'ielatter`being on -the shaft 29), is employed and power istransmitted therefromto the roll 24 by pulleys 38, 39 and a vbelt 40. The roll 24 is drivenat a peripheral speed `somewhat higher thanthe speed at which the sizedweb is. delive1ed` from the sizing tub, in order to pull it away fromthe size press, it being understood that the arc of contact between thepaper and the roll is very small and the tension is not sufficient toinjure the paper. The roll 25, however, is driven'at a somewhat slowerspeed so as to compensate for the shrinkage of the web during itsinitial drive.- As its. speed must be varied from time to time accordingtothe caliper or character ofthe paper, we,

preferably, employ a separate variable-speed power-'transmittingmechanism for driving the roll 25 from Vthe variable-speed drivmg lshaft 14,

-To vthis end the shaft of roll 25 is pro.- vided with af'lcone pulley41 driven by a belt'42 from a cone ulley 43 on a shaft 44 which, throughbeve gears 45, 46, receives its power from the shaft- 14." The rolls 28ofthe third series of thefirst ,tier aredriven at somewhat'higher speedvthan the" roll 2 5, but at a slower speed than the rolls 26 butstill'at .a higher peripheral' s eed than the travel of the web. Anysuitalile means may be utilized for drivingthe .rolls'28. We haveillustrated them, conventionally, as being driven by a pulley 47 `on'the shaft of the end roll 25. A belt 48 passes from the pulley 47 to thepulley 49 of the roll 28, which is' farthest from the roll 25,

and is ressed into engagement with the pulleys oythe intervening rollsIby intervening belt-tightening pulleys 50.

All of the rolls- 28, as' stated, may be driven at the same speed,since, as a practical matter, it is not essential that all of the rollsof the. series from end to end of the tier -should be driven atsuccessively slower speeds. il?.l p. y The series of rolls 27, locatedbetween those at`26 and 28, are driven at a surface vspeed higher thanthe travel of the paper,

but ata speed intermediate 'the speed of the rolls 26 and the rolls 28.For this purpose, the shaft 51 of one of the rolls 27 is provided withal pulley 52 driven by a belt 53 from a pulley 54 `on a shaft 55 drivenby bevel gears 56, 57 from the variable-speed maindriving shaft 14. Abelt 58 is engaged with pulleys 59 on the shafts of the rolls 27 byidler belt-tightening rolls 60, s0 that all of these rolls 27 are drlvenin unison.

After leaving the end roll 25 of the first tier of-rolls, the web ofpaper passes downwardly to the second tier (indicated as a whole at 12)and it then travels in the direction of the arrows in Figure 5 ,Whileresting on said rolls. The second tier of'rolls comprises three groupsindicated at 61, .62 and 63. The last roll of the group 63 has alarge-roll 64. The rolls 61 are all driven by the same belt 48 from theshaft of roll 25, by which the rolls 28 are driven. The rolls 62 aredriven from the shaft 55 by a pulley 65, a belt 66 and a ulley 67 Vonthe shaft of one of the rolls/6g. driven by a common belt 68 from theshaft 69.y The rolls 63 and 64 are all driven from a shaft 70 by bevelgears 71, 72. The shaft 70is driven from the main drivin shaft 14 byvariable-speed power-transmitting mechanism, including the two coneulleys 73, 74 with their belt 75, the cone pullley 73 being driven bypulleys 76, 77 and a belt 78 from the shaft 14, and the shaft 70 beingdriven from the cone pulley` 74 by pulleys..79, 80 and belt 81. Thethree groups of rolls in the second tier are drivenat progressivelydecreasin peripheral speeds.

The ro ls of the lowermost or third tier I are illustrated in Figure 6and they are illustrated as comprising thethree groups indicated at 82,83 ,and 84. As the web passes around the last large roll 64 of thesecond tier,'it drops a short distance and is then.

carried in the direction of the arrows by the rolls of the third orlowermost tier and 011e of the rolls 83, the shaft 93 itself beingdriven by a pulley 94 on the shaft 55, a belt 95 and a pulley 96 on saidshaft 93. The last group of rolls 82 are driven by a common belt 97 froma pulley 98 on the last roll 82 of the group. In passing over the thirdtier, where the paper is nearly dry, some slight tension may be exertedto keep the web from travelling sidewise, but this would not besuiicient to injure the paper.

The shaft' 198 may be driven from any suitable source of ower, but wehave illustrated it as being riven from a shaft 99 of The rolls 62 areall we will subsequently describe in detail. It

is sufficient for present purposes to state that the shaft 99 isprovided with a pulley 100, from which,`b a crossed 'belt 101 and apulley 102 on the ast roll 8,2, the pulley 98 1s rotated. The shaft 99is illustrated as providedwith a gear 103 to which power is transmittedfrom the"-variablesp'eed driving shaft 14 by variable speed powertransmitting mechanism.` This mechanism is illustrated as comprising abevel gear'104 on the shaft 14 intermeshing with and driving` r acomplemental gear 105 on a shaft 106.

This last-mentioned shaft is provided'with a cone pulley 107 whichtransmits power to a complemental cone pulley 108 by a beltv 109. Thelast-mentioned cone pulley 108 is on a shaft 110 having a pinion 111intermeshing with the gear 103.

It is desirable, or necessary, that the web of dried paper should beremoved from the drier'so as not to exert' tension on the web as it isbeing carried through the loft`and we, therefore, provide asupplementaldelivering or draught mechanism whichreceives the web as itemerges from the loft and feeds it to a roll-forming mechanism at suchspeed that' the'web is under no longitudinal constraint'at any pointbetween its entrance into the loft and its emergence therefrom.

Any suitable draught mechanism may be' utilized, but in any event itshould be capable of being driven at variable speeds under propercontrol. We have illustrated in Figs. 1^ and'4.- a draught mechanismwhich is suitable for the purpose and which will now be described.

This mechanism comprises two rolls 112, 113, one located above the otherbut spaced lapart so that the web is not' gripped thereby. These. tworolls are geared together so as to rotatesynchronously, one of the gearsbeing illustrated in Figure 6 at 114. The shaft 99 (previouslyreferredto) is' provided with a gear which intermeshes with that upon shaft 14,but which is not illustrated. Co-acting with the two rolls 112, 113 aretwo endless bands 115, 116 formed of ordinary cotton duck. felt, orother equivalent material. Each of these bands passes around a series ofidler rolls, those for the band 115 being indicated at 117, 118, andthose for the band 116 being indicated'at 119, 120. These idler rolls'for each band are so located that the band engages its associated large`roll through an arc of slightly less than 180. The `web emerging fromthe loft passes under an idler roll 121, then over one-of the rolls 118and passes, with the band 115, down under the draught roll 112, thencebetween the rolls 112, 113 and around the latter roll and out under oneof the rolls 120 to a reeling mechanism which is indicated as a whole atE. The web is gripped against the two rolls 112, 113 by the associatedendless bands 115,1116, which prevent any slippage of the paperrelatively to the rolls and ensures that the web will pass around therolls without pleating or wrinkling.

The two traction or draught rolls are driven by the variable 'speedmechanism from .the shaft 14, which we have previously I described andwhich includes the shaft 106, the shaft 99 and the intervening conepulle s. Assuming that the squeeze rolls'e, f o the` sizing tub aredriven at constant speed, so that the web of paper travels at aredetermi'ned speed `as it enters thel loft, 1t is possible for theattendant so to vary the s eed of the various rolls of the several tiers1n the loft and the speed of the draught rolls 112, 113, that the'paperwill be carried. through the'loft in such manner as to l`release it frommechanical constraint, which would prevent the. fibers -from shrinkingfreely during the drying o eration, and permit the paper to assume t atcockled appearance which is characteristic of high grade ,writing paper.

'We desire to -empha'sizethe fact that the web travels to all intentsand purposes'in substantially a single plane, notwithstanding the factthat as it passes from one tier of rolls to the other, it mustnecessarily deviate from that plane. tween the tiers ofrolls is so shortthat no length of the web is called upon to with- The distance betiallytangential to these rolls, both in passing to and leaving them. Again,while in the particular embodiment of the invention we have illustratedthe paper, in traveling over the several tiers of rolls, as passingalong paths which are substantially parallel, this is merely for thepurpose of reducing the necessary height of the loft, since each of thetiers of rolls could be. at an inclination.

After the paper has left the draught or traction delivery rolls 112,113, it may be subjected to tension in reeling it onthe reelingmechanism without injury to the paper, since the web is grippedfrictionally agalnst said rolls by the endless bands, and the tensionexerted on the web between the draught or traction rolls and the reelingmechanism is lrliot transmitted back beyond the traction ro s.

'As previously indicated we find that, by means of an apparatussubstantially as herein described. it is possible to carry the paperthrough the loft at high speed without exerting a tension thereon orsubjecting it to longitudinal constraint. Conselquently, we are able tomaintain the drying-atmosphere of the loft at a high tem-v peraturewithout danger of injuring xthe web, for we have found it practical toheat thedryingatmosphere to a temperature of 240 F.

.- Any suitable means may be employed for 'heating the air in the loftand for delivering heated air thereto.

)Ve have -illustrated means which may be employed for this purpose.Above the casing which constitutes the loft or'drying-chamber (andwhich, by the way, is of sufficient width to -receive the widest web of-paperproduced in the mill) we rovide a second chamber which is practicay double the-width I of the loft. This second chamber is indicated inFigure 2 at 121 and comprises end and side walls and a suitable cover-ortop wall. Thechamber is separated from the loft by a Hoor or par- 2otition. -Heatedfffresh air is supplied to one side of thischmbenintermediate its ends, a trunk or conduit 123 which may be4provided with a manually controlled damper 124. Communicating with thisconduit 'there is '-a fan 125, the inlet to which communicates with aninlet chamberv 126 provided with any suitable heating means by Awhichthe air'entering the same may be fend of the loft.

In the air chamber 121 we have illustrated three separate air heatingunits indicated at 130, 131 and 132, through which the air is circulatedand by which it may be heated to a high temperature.' In lieu of threeseparate units, which overlap as shownin-Figure 2, we might, of course,employ a single heating unit extending across the air chamber 121 andprovided with the proper number of steam coils or pipes to supply thenecessary radiating surface. These heating units are located relativelynear the right hand end of the airchamber, and to the' right of v themouth of the trunk or air duct 123.

It is desirable that the air should be delivered in proximity' to thethree tiers of rolls, so that currents of air will travel lengthwiseofthe paper passing over the rolls and thence back up into theairchamber 121. For this purpose we provide three air conduits indicated at133. 134 and 135, all of which communicate with an upright trunk ormanifold 136 which is arranged at the left hand end of the machine andwhich extends-downwardly to one side of the loft. At the inlets of thesethree ducts' are placed fans 137,` Avcrhiclij the'heated .air may beforced therethrough into theA up.

right manifold or duct,.136. From the vertical manifold 136- there arehorizontal trunks `140, 141 through which. the-heated air issues intothe loft a-t the left handend thereof. The duct 140 is located betweenthe top and the intermediate tiers of rolls, and the duct 141 liesbetween the intermediate and the lowest tiers -of lrolls. These ductshave open mouths or delivery noz'zles 142, 143, respectively, wh'ichdirect the-air towards the right hand end' of the'l machine under thoseportions of the web which are traveling on the upper and intermediatetiers of rolls.

For supplying heated air to the loft above the level of the paper on theupper tier of rolls, we employ a 4conduit 144 which leads from' thetrunk 133, as is best shown in Figures 1` and 2. This'last mentionedduct 144 has a vmouth or nozzle 145 Ywhich delivers the air into theloft above the upper tier of rolls, so that a current of air will passalong the web thereon to the right hand end of the loft. From the spacein the loft ordrying chamber above the upper tier of rolls the air maypass to the'air chamber 121 through an opening 146. For conducting theair back into the chamber 121 from levels between the first andsecondand second and third tiers of rolls, we provide outlets 147', 148in the side wall of the loft or ldrying'- chamber which communicate witha large duct or trunk 149 (see Figure 3) 'Which opens into thev floor ofthe chamber 122 through the large opening 150 (see Figure 2). Theexhaust fan 128 has its inlet communicatin with the air chamber 122through t e right hand end wall thereof, above the openlng 146, as shownin Figure 1^, taken in connection with Figure 3.

The drawings illustrating the mechanisms described are more or lessdiagrammatic and conventional and, of course, the larrangement as wehave describedit-maybe modilied or changed in many particulars. The

ros

point is that the'appa'ratus, as a whole,.com

prises a large chamber, separated from the drying chamber or loft, inwhichthe air5 may be heated by suitable heatin elements and from whichit may be cause to circulate at relatively high seed in currentsdirected longitudinally o the travel of the web against both facesthereof. In. addition to these instrumentalities, we employ a fan for suplying continually a certain amount of resh highly heated air to the aircham-ber, -and a fan for exhausting from the chamber approximately asmuch air as is delivered thereto by the inlet fan. By constantlysupplying fresh air and exhaust ing a portion of the used air, whichcontains a relatively high moisture content, and by utilizing, inaddition, the internal fans Ithrough the loft and were v. not circulated'again and again therethrough a greater amount o f heat would benecessary initially to heat the entire volume of air to the propertemperature. Vhile, of course, we prefer i to re-heat a portion oftheair which has already been utilized in drying a web, and using it again,we would not consider it a ldeparture from the spirit and scope of-ourinvention if the air were passed only once through the loft or dryingchamber.

In an apparatus such as herein described, in which the internal heatingelements are utilized forheating the re-circulated air, we regard it asdesirable to have the hea-ted fresh air delivered to the air chamber foradmixture with the air after it has been .heated by the internal heatingelements and it is for this purpose that the outlet of the duct 123, atlts point of entrance into the air chambergis located between there-heating velements and the fans or blowers which deliver the air tothe loft or drying chamappearance as ber. yPreferably the air passingthrough this Vduct 123 is'heated to a temperature of approximately 240F., and the -heating ele- 130, 131, -132 are kept at said temperamentsture, so tained at a F. In operating our apparatus, care should be takento prevent the atmosphere at any point in the whole apparatus fromreaching that the re-circulated air is maina temperature lower than thedew point in` order that condensation of moisture may be eliminated, forreasons which will be readily understood by those skilled in the art.

Recapitulating what has been explained in this specification, it may bestated thatthe web of paper as delivered from the dry end of theinitial'pa-per making machine preferably has a moisture -content of 10%when delivered to the sizing tub. In passing through the loft or dryingchamber the web,

being under no mechanical constraint and not having to support its ownweight, the fibers are permitted to dry and shrink in substantially thesame way that they are when the paper is hung over poles in the usualloft, so that it has the same coekled the best loft dried paper, but hasa firmer tone and greater strength. The speed of travel of the paperthrough the drier and th'e temperature of the drying atmosphere may beso related that the web` on leaving the drier` has a moisture content.of approximately 5 to 6%, although. if desired, the drying may beproceeded with to such au extent that the web has a much lower moisturecontent. vWe, however, do not regard this as so desirable when the paperis to be subsequently finished.

. We have provided in connection 'with the vtion of their travel.

temperature approximately 240?V drier a novel mechanism forautomatically feeding or threading the end of a web of paper throu h theloft. This feeding mechanism comprises two tapes 151, 152 which arenarrow in width and by which a tail 153 on the end of a web154'(see-Figure 8) may be gripped and carried, over the various tiers ofrolls. These two tapes have confronting vfaces throughout the greaterpor- At the receiving en of the machine they are separated by a bar 155.as .s'hown in Figure 1,so' that when the tail 153 is formed into a wadby the machine l attendant, it can be insertedfbetween the two ta'pesand carried by them as they travel through the drier. These two tapesare passed over the upper tier of rolls, thence downwardly around thelarge roll 25,`at the right, end thereof, thence back over the secondorintermediate tier ofvrolls, thence down under the large roll 64' to 'thelower tier ofn rolls, whence they pass around a supplemental roll 156below the delivery slot in the end wall of the loft and back to a roll157. Iassing upwardly from the roll 157, the tapes are lseparated by thebar 155 and then meet as they pass over the first roll 24 of the firsttier. The tapes which are thus in facial contact throughout practicallyall of their travel track over the rolls with which they engage at oneextreme end thereof, where they are out of the normal path of travel ofthe paper web as it passes through the loft or drier.

-lVhen the tail wad is inserted between the two tapes. the tapes carryit and the succeeding length of the web along the first tier of rolls,thence back over the second lier of rolls and forwardlvover the thirdtier of a rolls until the 'wad is delivered at the delivery slot in theend wall of the dryingv chamber. where it is caught b v the attendant,and pulled out from the tapes and thence passed to the-traction ordraught instrumentalities. rl`lier. .fo1e, the web of paper. which hasbeen 'traveling slightly diagonally. is `caused to pursue a rectilinearpath through the drying chamber.

Having thus explained the nature. of our said invention and described away of malt'- ing and using tli'e same, although without attempting toset forth all of the forms in which' it may be made or4 all of the modesof its use. what we claim is:

1. A paper drying apparatus comprising 1 chamber, a plurality of groupsof Vrolls urranged in a continuous series therein over which a web ofwet paper may be passed in a plane tangential thereto, and means forrotating said groups of rolls at different speeds.

3. A paper drier comprising adryin chamber-a plurality of vertically.spaced horizontal tiers of rolls therein, on which al continuous web ofpaper may travel in suc .cession without the formation of dependentloops between adjacent rolls, the last endY a continuous web of papermay travelin succession without the formation of de- 5. A paper driercomprising a dryingchamber, a plurality of vertically spaced horizontaltiers ofrolls therein whereon the web of paper mayt'r'avel over therolls from each tier to the next succeeding tier without the formationof dependent loops between adjacent rolls, the rolls over which thepaper travels from one tier to the neat succeeding tier being of largerdiameter than the remaining rolls, means for rotating said large 'rollsto impart thereto a peripheral speed equal to the desired speed oftravel of the web, and means for rotating the relatively smaller rollsto impart thereto a peripheral speed greater than the desired speed oftravel of the web. l

6. In combination, a casing, means for positively feeding a web of moistpaper into said casing to be dried therein, means for positively feedingthe dried web out of said casing at a speed sufficiently lower than thefeeding in speed to compensate for the shrinkage of the paper during thedrying operation and impart notens'ion to. the web within said casing,and means forsupporting and carrying forward the web in said casingwithout substantial restraint in any direction while it is being dried.

7. In combination, a casing, means for positively feeding a web of moistpaperinto saidcasing to be dried therein,.means for positively feedingthe dried web out of said casing at a speed sufficiently lower than thefeeding in speed to compensate for the shrinkage of the paper during thedrying operation and impart no tension to the web within said casing,means for supporting and carrying forward the web in said caspaper drier-comprising a drying without substantial restraint in any diforpositively feeding the dried web out of said casing at a speedsufficiently lower than the feeding in 'speed' to compensate for theshrinkage of the paper during la drying operation and impartl no tensionto the web within saidv casing, means for supporting -and carryingforward the web in'said casing comprising rolls on which the web rests,and rolls over substantial arcs of which the web engages, means fordriving said first mentioned rolls with a'surface velocity greater than.the velocity ofthe web resting thereon, and means for driving said lastmentioned rolls with surface velocities equal to that of the webengagingthereover.

9. In combination with a casing, of means forpositively feeding a web ofmoist paper into said casing to be dried therein, means for positivelyfeeding the dried web out of said casing at a speed suieientlylower'than the feeding in speed to compensate for the shrinkage of the'paper during a drying operation and impart no tension to the web withinsaid casing, means for supporting and carrying forward the web in saidcasing' comprising rolls on which the web rests, and y rolls oversubstantial arcs of which the web engages, means for driving said firstmentioned rolls with 'a surface velocity greater than the velocity ofthe web resting'thereon,

and means for driving said last mentioned rolls with surface velocitiesequal to that of the web engaging thereover, said last mentioned rollsbeing positioned at int-ervallls' between groups of said first mentionedro s.

10. In combination,a casing, means for positively feeding a web of moistpaper into said casing to be dried therein, means for positively feedingthe dried web out of said casing at a speed sufficiently lower than thefeeding in speed tol compensate for the shrin tage of the paper duringthe drying operation and impart no tension to the web within saidcasing, means for supporting and carrying forward the web in said casingcomprising 'superposed tiers of' rolls on which the web rests and rollsat the ends of said tiers over substantial ares of which the web engagesin passing from one tier tov the next, means for driving said firstmentioned rolls at a surface velocity greater than that of theweb'resting thereon, and means --for driving said second mentioned rollswith surface velocities equal to those of the web engaging thereover.

11. In combination, a drier casing, means for positively feeding a webof moist paper into said casing to be dried therein, means forpositively feeding the dried Web out of said casing at a speedsuficiently lower than the feeding in speed to compensate for theshrinkage of the paper. during the drying operation and impartnontensio'n thereto Within said casing, and feeding mechanism in saidcasing closely engaging the Web and moving at a speed intermediate thespeeds of the feeding in and feeding out means.

l2. In combination, a drier casing, means for positively feeding a webof moist paper into said casing to be dried therein, means forpositively feeding the dried Web out of said casing at a speedsufliciently lower than the feeding in speed to compensate for theshrinkage of the paper during the drying operation and impart no tensionthereto Within said casing, feeding mechanism in said casing closelyengaging the web and moving at a speed intermediate the speeds of thefeeding in and feeding out means, and feeding means in said casing withwhich the web loosely engages, movable at a higher speed than saidmechanism. v

In testimony whereof We have afiixed our signatures.

HUGO H. HAN SON. WILFRED A. WYLDE.

